title: [A comparative study of early degradation of PLLA and PLGA rods at various sites in rabbit].
abstract: This study was designed to assess the effect of implantation site and environment on early in vivo degradation behaviors of poly(L-lactide) (PLLA) and poly(L-lactide-co-glycolide) (PLGA) copolymer. The rods were implanted at two sites in each of 24 New Zealand White rabbits. The first site was within the suprapatellar bursa of the joint cavities (JC) and the second site was in the opposite condyles of femurs (CF). Three rabbits of each group underwent explantation of rods after 4, 8, 12, and 16 weeks. At each interval, measures were taken to evaluate the molecular weight, shear strength, weight loss and thermal properties of PLLA and PLGA. It was found that PLGA degraded slightly faster than PLLA. After 16 weeks, PLLA's initial inherent viscosity of 4.6 decreased to about 3.4 in both implantation sites while that of PLGA decreased from 4.6 to about 2.2. Both PLGA and PLLA showed enough shear strength retention in 16 weeks (> or = 53MPa) within 16 weeks. Autocatalysis mechanism was confirmed by the fact of accelerated weight loss of PLGA after 8 weeks and of PLLA after 12 weeks. The results revealed that PLGA could be a promising candidate material as a replacement of PLLA in internal fixation of bone fractures, and no significant difference of early in vivo degradation behaviors between PLLA and PLGA was observed in regard to different implantation sites in 16 weeks.
authors.affiliation: Chengdu Institute of Organic Chemistry, Chinese Academy of Sciences, Chengdu 610041, China.
authors.forename: Di
authors.initials: D
authors.lastname: Pang
authors.forename: Jingbing
authors.initials: J
authors.lastname: Ye
authors.forename: Dongliang
authors.initials: D
authors.lastname: Chen
authors.forename: Jian
authors.initials: J
authors.lastname: Li
authors.forename: Chengdong
authors.initials: C
authors.lastname: Xiong
authors.forename: Qing
authors.initials: Q
authors.lastname: Li
mesh_terms: D020341:Absorbable Implants; D000818:Animals; D001858:Bone Nails; D005260:Female; D020007:Implants, Experimental; D016268:Internal Fixators; D019344:Lactic Acid / Q000737:chemistry / Q000378:metabolism*; D008297:Male; D011091:Polyesters; D011100:Polyglycolic Acid / Q000737:chemistry / Q000378:metabolism*; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011108:Polymers / Q000737:chemistry / Q000378:metabolism*; D011817:Rabbits
chemical_list: D011091:Polyesters; D011108:Polymers; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011100:Polyglycolic Acid; D019344:Lactic Acid; C033616:poly(lactide)